A hydraulically actuated downhole pump assembly for producing a well is known to those skilled in the art, and takes on all sorts of different forms as evidenced by the cited patent to George K. Roeder, to which reference is made for further background of this invention. Reference is also made to the additional art cited in the Roeder patent. These various type production pumps are powered by a fluid that is pumped downhole to an engine which forms part of the pump assembly. Another part of the pump assembly is a pump which is connected to a source of formation fluid so that the engine drives the pump and the pump lifts or produces fluid to the surface of the ground.
The pump usually is located at the lower end of the pump assembly while the engine is usually located at the upper end of the pump assembly, so the upper end of the pump assembly is referred to as the engine end while the lower end thereof is referred to as the pump end, and the engine end together with the pump end make up the pump assembly.
The pump end has a pump barrel and a pump piston reciprocatingly received in sealed relationship within the pump barrel. The engine end has an outer engine barrel, and an engine piston is reciprocatingly received in sealed relationship within the engine barrel. A valve assembly is provided for controlling the various flow paths of fluid associated with the pump assembly.
The valve assembly heretofore has been spaced from the engine piston and includes a valve element that moves up and down between two positions in order to align various passageways of the engine end and pump end of the pump assembly in a manner to alternately apply power fluid to force the engine piston to reciprocate. A control rod is often used in prior art pump assemblies to shift the valve element between the two alternate positions at the end of each stroke of the engine piston. This configuration of a pump assembly can become very complex, and the engine end usually demands very close tolerances be used therein which calls for expensive fabrication techniques.
This invention provides improvements in the engine end of a downhole pump assembly and particularly a new and improved valve assembly for the engine end of a pump assembly, wherein the engine end has a valve assembly that receives an engine piston therein that is reciprocated by power fluid in a novel manner.
This patent application is directed to those skilled in the art, and particularly to one who comprehends the prior art cited herein.